найти с нок.
найти с нок.
дроби к общему знаменателю.
и

и

Пошаговое объяснение:

1/27 + (7/9 - 2/3) = 4/27

1) 7/9 - 2/3 = = 7/9 - 6/9 = 1/9

    9 = 3 * 3 * 1

    3 = 3 * 1

    НОК (9 и 3) = 3 * 3 * 1 = 9  

    9 : 9 = 1

    9 : 3 = 3

2) 1/27 + 1/9 = =1/27 + 3/27 = 4/27

    27 = 3 * 3 * 3 * 1

    9 = 3 * 3 * 1

    НОК (27 и 9) = 3 * 3 * 3 * 1 = 27

   27 : 27 = 1

   27 : 9 = 3

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42 - 9 3/4 - (11 7/12 + 2 5/18) = 18 7/18

1) 11 7/12 + 2 5/18 = = 11 21/36 + 2 10/36 = (11 + 2) + (21/36 + 10/36) = 13 31/36

  12 = 2 * 2 * 3 * 1

  18 = 2 * 3 * 3 * 1

  НОК (12 и 18) = 2 * 2 * 3 * 3 * 1 = 36

  36 : 12 = 3

  36 : 18 = 2

2) 42 - 9 3/4 = 41 4/4 - 9 3/4 = 32 1/4

3) 32 1/4 - 13 31/36 = 32 9/36 - 13 31/36 = 31 45/36 - 13 31/36 = 18 14/36 = 18 7/18

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8/11 и 5/8  =  64/88 и 55/88

11 = 11 * 1

8 = 2 * 2 * 2 * 1

НОК (11 и 8) = 2 * 2 * 2 * 11 * 1 = 88

88 : 11 = 8

88 : 8 = 11

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7/35 и 61/63 = 35/315 и 305/315

35 = 5 * 7 * 1

63 = 3 * 3 * 7 * 1

НОК (35 и 63) = 5 * 7 * 3 * 3 * 1 = 315

315 : 35 = 9

315 : 63 = 5